Guest levelhead86 Posted July 22, 2004 Share Posted July 22, 2004 Hey guys... simple or complex question depending on how you look at it but here you go: I got a 1979 280zx (very cool). Anywho... it runs, but only under the circumstance that you don't have the hose connecting the airflow meter to the throttle body on there. Literally as soon as you plug that sucker into the air flow meter, the thing chokes out and dies. Also, the car acts the same way if you move the flap on the inside of the air flow meter. Weird stuff, so I was wondering if it's the air flow meter itself (which i tested electonically, and it passed) or maybe the throttle body? I also noticed that when running(obviously with the hose unattatched), it sounds like it's gasping for air, with a REAAAAALLY loud hissing sound coming from the throttle. I just replaced the ECU with a remanufactured one, so that's definately in good working order so I'm STUMPED. Thanks a bunch. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted July 23, 2004 Share Posted July 23, 2004 Thats really strange... if the boot between the AFM and the throttle body is off, then the car.. well, shouldnt run! The air rushing past the flap (suction basicaly) in the AFM is the main sensor the computer uses to control the FI..(along with the tps, temp, ect) ...and it dies when you put the boot on?!? hmmm.... I'd say check the AFM for mechanical damage or wear.. maybe the flap is sticking/bent? or maybe something is cloging the boot from the air filter to the AFM... Have you checked all the electrical conections to the AFM/TPS/ect? Quote Link to comment Share on other sites More sharing options...
Guest levelhead86 Posted July 23, 2004 Share Posted July 23, 2004 I checked all the AFM connections with the ohmeter and they're good, but notabley, all the connections to the sensors show some corrosion (green), implying maybe a short originally (the car, when I got it, had a 1983 ECU, and the car/engine is definately a 1979), but I've since changed the ECU to a rebuilt '79 so that's not likely the culprit. As for the air filter, I've even taken apart the whole assembly so that JUST the AFM, and rubber to the throttle body were there and STILL, it choked out the engine. Mechanically, the flap moves very easily and has no rust at all... I talked to an uncle of mine with a similar system in his old porche, and he said it could be the hemispherical spring retaining the flap is rusted or broken, forcing the flap to move to much despite the under-abundance of air, thus drowning the engine in gas to comensate for air that's not even really there, but i doubt that...Like I said, all the sensors have signs of corrosion, so maybe it's electrical gremlins? Damn the confusion! thanks for your help so far, and I'll try to keep y'all posted if i see any changes.... Quote Link to comment Share on other sites More sharing options...
datsunlover Posted July 23, 2004 Share Posted July 23, 2004 Do you have the other computer still? It wouldnt hurt to throw it in to see what it does.. And you should clean up those coroded loking conections.. and put some di-elecrtic grease on them. I think I will agree with your uncle.. might be a bad spring in the AFM..or a 'dead' spot on the circuit board/contact point (inside the AFM)... have you cut the glue on the black cover (on the side of the AFM) and looked in there? I'd try adjusting the spring tension (assuming the spring is good) in the AFM... Just hold onto the wheel with all the teeth on it, and crack the retaining screw loose. (its held on with red glue most likely) Carefully move the wheel a few teeth (tightening it) and lock the screw back down. (if you let go of the wheel now, it will unwind the spring and then, well.. that just sucks.. ask me how I know!) Fire it up and see how it runs... You might have to play with it for a bit to get it to run right, (repeat the process a few times.. one or two teeth at a time.. and try going loose and tight to see if there's any change) but then again, it might be someting else... Although the AFM is ussually the big prob with the ol' Z FI.. along with the TPS.. Have you tested that with the ohm meter? Quote Link to comment Share on other sites More sharing options...
Guest levelhead86 Posted July 30, 2004 Share Posted July 30, 2004 the car is running now,and well at that... I took apart the airflow meter, and found there was no tension on the spring at all. I tightened that, and also gave the mixture screw a good twist and BANG! the thing ran so good, I had to blow a few donuts to celebrate, heheh. Thanks for everything dude, I really owe ya'. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted July 30, 2004 Share Posted July 30, 2004 No problem man, glad I could help you out. Good to hear it's fixed! Always nice to hear a dead Z come back to life and lay down some rubber! Quote Link to comment Share on other sites More sharing options...
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